Shmoo plot
Beginner
A grid that shows where a chip works and where it fails as two settings change, such as speed and voltage (how hard the electricity pushes).
Novice
A grid of pass/fail results for one test as two conditions are swept, usually supply voltage against clock speed, at a fixed temperature. The boundary between pass and fail shows the chip’s real operating limits.
Expert
The shape is diagnostic. A boundary that slopes with voltage is the normal speed limit; fails at high voltage and low speed, holes inside the pass region, or ragged edges point to hold-time, noise or marginal analog problems. Repeated across many parts and temperatures to build the operating envelope.